Although Windows and Linux were traditionally viewed as competitors, modern IT advancements have ensured much needed network availability between these ecosystems for redundancy, fault tolerance, and competitive advantage.
Newer software innovations enable the dynamic transfer of data and their processing to the best environment for any given purpose. That may be on-premise, in the cloud, in containers, in Windows, or in Linux. Traditionally, dynamically and securely transferring resources from Windows to Linux was not possible because each operating system had respective methods and tools for availability which are not interoperable.
In the case of SQL Server, there are three chief distinctions that account for this inability to dynamically transfer data and processing between its native cluster resource manager (CRM), Windows Server Failover Clustering, and a Linux based CRM such as Pacemaker:
- Communication: Windows supports two-way communication between its CRM and SQL Server. Linux only supports one-way communication with SQL Server, initiated by its CRM.
- Coupling: Partly because of the communication, there’s tight coupling between SQL Server and Windows Server Failover Clustering. Changes in the former are propagated into the latter—and vice versa. The coupling is much looser in Linux; Pacemaker doesn’t see changes made in SQL Server.
- Windows Integration: One can configure availability groups with SQL Server using Windows’ authentication (such as domain accounts). Certificates are required to configure availability groups in Linux.
These distinctions are easily overcome with software that facilitates the rapid creation of high availability for SQL Server instances, availability groups, and Dockers containers in Linux and Windows—with just a few clicks.
Without this software, there are numerous facets of firewall configurations, passwords, node authentication, and node certification organizations must tend to when transferring resources between these environments. The software simplifies these concerns for easy accessibility to an assortment of secure settings to position IT assets not only for business continuity, but also for competitive advantage.
Smarter availability software enables clusters across multiple Linux distributions—which isn’t possible using Linux’s CRM. Since the software supports mixing nodes across Windows and Linux distributions, it’s essential to configure firewalls to permit availability between these operating systems. Doing so involves adding a HA option on the latter’s firewall to transfer resources when the firewall’s enabled. Partly because this addition alters this firewall’s rules, organizations must reload this additional HA service for the firewall on each of the Linux cluster’s nodes for availability. A best practice for transferring computational resources for availability is to have more than one node available in a cluster for doing so. In several cases administrators must take care to manage these nodes individually. Although adjusting the firewall simply requires a basic line of code, it must be input on each node in the Linux cluster to permit data into the network from SQL Server as an option.
The software also reduces the complexity of high availability between Windows and Linux settings via its passcode administration. With traditional HA methods, users must install Linux’s CRM, create accounts on each of the available servers, and assign passwords to them. With availability techniques, organizations swiftly install its third-party resource manager and assign a passkey to the nodes, then join the nodes for holistic cluster management through a UI. The manager provides a consistent experience for each of the cluster’s nodes. With traditional HA measures between SQL Server and Red Hat, for example, users have to input the same password on each server for holistic cluster management through any of the nodes. Failing to do so can increase time and costs when switching resources between nodes. The UI of the availability method, however, obfuscates this concern while empowering organizations with comprehensive management of each of the cluster’s nodes—without undue emphasis on passwords.
The authentication process is much less complicated using availability software than it is using conventional HA methods. Activating a three-node cluster of Red Hat, Ubuntu, and Windows Server with the former approach takes less than a minute. Simple drag-and-drop capabilities create the subsequent availability group in seconds, much easier than creating one in Linux. Authenticating the various instances requires a simple click and input of a password. Without availability software, users must enable Linux’s CRM and resources like Corosync and Domain Name Systems for uniformity of experience of each node in the cluster. This process is more time-consuming and resource intensive, partly due to relying on domain names instead of host names. Newer availability methods simply require users to create a Vhost—a virtual IP address and virtual host name—and select the nodes to run on it. Host names pose no complications in Windows; in Linux, they must be manually added to the host file. In this respect, the Vhost option conserves time, effort, and valuable enterprise resources for the authentication process.
Node certification is another necessary Linux authentication step that’s unnecessary in Windows. Domain accounts can be used for authentication in Windows, whereas formal certificates are required in Linux. These are replicated and sent to each node in the cluster. Availability software can bypass this step while still providing HA for Docker containers and instances. With a few clicks, users can create additional Vhosts to add instances or containers as desired. Meanwhile, they get the same secure environment without needing certificates.
Security and Availability
The aforementioned practices are by no means an exhaustive list of the procedures required for implementing availability between Windows and Linux clusters. Nonetheless, they enumerate some of the most vital steps for preserving the security and underlying integrity of the data (and their processing) transferred between these environments. Organizations shouldn’t sacrifice security to position resources between operating systems; using these best practices, they won’t.